In recent years, toners (colorants) for special colors such as gold, silver and fluorescents have been developed. A decolorable toner that can become substantially colorless with heat has also been developed. Image forming apparatuses which can form images with full standard colors and special colors have thus been developed. However, since typically an image forming apparatus requires inclusion of an image forming station for the special color(s) in addition to those for full standard colors, there is a problem with increasing cost for such systems.